Don't feed me this BS about it being for the safety of the player. Soccer doesn't need a rule like this, neither does rugby or basketball. That's a hilariously bad reason.
As far as the substitution thing goes, isn't that the point of the offense? To get any advantage possible against a defense? And so they found a way to do that, so instead of making the defense finds a way to adjust, we're going to candy them?
This guy.